Field of the Invention
The present invention relates to a trailing arm bush for CTBA that connects between a pair of trailing arms supported by a torsion beam disposed in a vehicle width direction and a vehicle body, and more particularly, to a trailing arm bush for CTBA in which by forming three bush rubber units for connecting between an inner peripheral surface of an outer pipe and an outer peripheral surface of the inner pipe, a bush rubber unit can have characteristics of a non-linear spring when the inner pipe moves back and forth by external vibration of the vehicle, and a gap between the inner pipe and a stopper is secured to significantly improve an abnormal noise generation phenomenon.
Description of Related Art
In general, a suspension system of the vehicle is constituted by various devices for improving the riding comfort of the vehicle, such as, a chassis spring that connects an axle and a vehicle body to alleviate impact receiving from a road surface during running, a shock absorber for absorbing a free vibration of the spring, and a stabilizer for preventing the vehicle from rolling from side to side.
Such a suspension system is classified into a front wheel suspension system and a rear wheel suspension system depending on mounting parts of the vehicle, and is classified into an integral axle suspension type in which left and right wheels are connected to each other by one axle, and an independent suspension type that is connected to the left and right wheels so as to be independently operable.
Since the independent suspension type is able to lighten the lower weight of the spring and lower the bottom of the vehicle body, riding comfort is good, and grounding characteristics and steering stability are excellent. Thus, it is mainly widely used in passenger cars or the like.
Meanwhile, in recent years, as the suspension systems of medium and small-sized cars, application of a Coupled Torsion Beam Axle (CTBA) type suspension system which has a simple structure, can be reduced in weight, has the small number of required components, and has excellent workability has expanded.
Generally, the CTBA type suspension system is a type of a torsion beam axle, and is called a twist beam suspension or a coupled link.
Such a CTBA type suspension system is constituted by a trailing arm which is treated as a rigid link and on which all the parts are mounted, a torsion beam that mainly controls the effect on the rolling behavior of a vehicle and serves to restrain the movement of the trailing arm relative to roll stiffness and left and right lateral force, and a trailing arm bush for CTBA that alleviates the vibration and shock from the ground surface.
The CTBA type suspension system having such a configuration is characterized in that there are two supporting points connected to the vehicle body smaller than other suspension systems, but directions of the input load are diverse, and values of relatively large sizes are input.
Therefore, there are great changes in performance of the vehicle depending on the performance of the trailing arm bush for CTBA, and the trailing arm bush for CTBA will occupy an important role in terms of riding comfort and driving stability of the vehicle.
As shown in FIGS. 1 and 2, the structure of the trailing arm bush for CTBA according to the related art has a form in which a bush rubber unit 3 and a void part 4 are provided between the outer pipe 1 and the inner pipe 2, and a stopper 5 is attached to the inner peripheral surface of the outer pipe 1.
As shown in FIG. 1, a so-called two-bridge type trailing arm bush for CTBA configured to connect two parts between the outer pipe 1 and the inner pipe 2 has good characteristics in terms of handling of the vehicle and durability of the bush, but there is a disadvantage in that riding comfort of the vehicle is lowered to induce Impact harshness.
Meanwhile, as shown in FIG. 2, a so-called four-bridge type trailing arm bush for CTBA configured to connect four parts between the outer pipe 1 and the inner pipe 2 has an advantage in that the riding comfort is excellent as compared to the two-bridge type, but has a disadvantage in terms of handling of the vehicle and durability of the bush.
That is, since handling and riding comfort of the vehicle are inversely proportional to the trailing arm bush for CTBA, there is a need for trade-off between two characteristics at the time of actual design, but there is a problem in that it is very difficult to optimize the trailing arm bush for CTBA while satisfying both two characteristics.
Thus, there are problems such as prolonged development period and consumption of extra development costs due to the extra number of tests, when developing a trailing arm bush for CTBA depending on the design of the conventional trailing arm bush for CTBA.
Furthermore, as shown in FIG. 2, since the conventional trailing arm bush for CTBA is primarily designed so that a very small gap 6 of 0.5 mm is formed between the stopper 5 and the inner pipe 2, and the four-bridge type trailing arm bush for CTBA has the spring characteristics of the six-bridge type, there is a problem in that a lot of abnormal noises occur.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.